Elongated switch bar apparatus

ABSTRACT

A keyboard encoder comprises a set of keys. Each key is in juxtaposition with one or more field-responsive elements associated with that key, the outputs of the field-responsive elements being conveyed to output terminals of the encoder. Actuation of a key alters the field to which the elements associated therewith respond. The number of elements associated with each key and the connections of these elements to the output terminals correspond to the output code for the character represented by the key. Consequently, the responses of the fieldresponsive elements to actuation of a key provide a directly encoded representation of the corresponding character at the output terminals. Also disclosed is an elongated switch bar in which contact is readily made even though the switch bar is depressed at either of the two ends thereof.

' United States Patent Gabor [15] 3,665,126 [4 1 May 23, 1972 [54]ELONGATED SWITCH BAR APPARATUS [60] Division of Ser. No. 598,558, Oct.10, 1966, Pat. No. 3,588,875, which is a continuation of Ser. No.496,031, Oct. 14, 1965, abandoned.

52 vs. C] ..200 5 E, 74/483, 200/18,

340/365 51 rm. Cl. ..H0lh 9/26 [58] Field of Search ..200 5 E, 18; 340173; 74/483 [56] References Cited UNITED STATES PATENTS 2,932,816 4/1960Stiefel et a] ..200/5 E Primary E.xaminer-Gerald Goldberg Attorney-LouisEtlinger ABSTRACT A keyboard encoder comprises a set of keys. Each keyis in juxtaposition with one or more field-responsive elementsassociated with that key, the outputs of the field-responsive elementsbeing conveyed to output terminals of the encoder. Actuation of akeyalters the field to which the elements associated therewith respond.The number of elements associated with each key and the connections ofthese elements to the output terminals correspond to the output code forthe character represented by the key. Consequently, the responses of thefield-responsive elements to actuation of a key provide a directlyencoded representation of the corresponding character at the outputterminals. Also disclosed is an elongated switch bar in which contact isreadily made even though the switch bar is depressed at either of thetwo ends thereof.

7 Claims, 6 Drawing Figures Patented May 23, 1972 4 Sheets-Sheet l FIG.|

INVENTOR. WILLIAM D. GABOR KMQ W ATTORNEY Patented May 23, 1972 4Sheets-Sheet If,

I INVENTOR.

WILLIAM D. GABOR @MR #JM ATTORNEY Patented May 23, 1972 3,665,126

4 Sheets-s 4 92 so 2 a) v //////7// 1 9 & FIG.6 VENT I WILL! 0G R BYRMRW TORNEY ELONGATED SWITCH BAR APPARATUS This application is adivision of my co-pending application Ser. No. 598,558, filed Oct. 10,1966 for Character Encoder, now U.S. Pat. No. No. 3,588,875, issued June28, 1971, which in turn is a continuation-in-part of another applicationSer. 496,031, filed Oct. 14, 1965 for Keyboard Encoder, now abandoned.BACKGROUND OF INVENTION This invention claim to a compact keyboardencoder having no moving parts except for the keys themselves. Actuationof a key changes an electrical characteristic of one or more sensorsaccording to the coded representation of a character associated with thekey. Converters in the encoder transform these changes in thecharacteristic to digital signals identifying the character.

A digital encoder of the type having a keyboard input provides the linkbetween a human operator and automatic data processing equipment. Thekeyboard appears similar to a typewriter keyboard and for each keyboardcharacter selected by the operator, the encoder produces a series ofelectrical signals corresponding to the digits in a coded representationof the character. In an illustrative application, the operator uses thekeyboard to type computer instructions and input data. The encoderconverts the selected characters to their corresponding digital signals,which are then recorded on a magnetic tape or on a series of punchedcards.

Many prior keyboard encoders employ keyboards having mechanical linkagessimilar to those in conventional office typewriters or teletypemachines. High operating noise and relatively frequent maintenance, dueto wear and maladjustment, restrict the performance of such mechanicalencoders.

Electrical switches having moving contacts are also used in priorkeyboard encoders. However, dirt on the contacts and contact oxidationand wear cause mechanical switches to have varying non-zero resistancesbetween engaged contacts. As a result, encoders employing movingcontacts have limited reliabilityand their performance oftendeteriorates with age as well as with use.

A further disadvantage of prior keyboard encoders is their relativelylarge size and high cost.

BRIEF SUMMARY OF INVENTION terized by relatively low cost;

Another object of the invention is to provide an encoder of the abovetype characterized by the absence of mechanical linkages and movingelectrical contacts.

A further object of the invention is to provide an encoder of the abovetype characterized by high reliability. A more specific object of theinvention is to provide a keyboard encoder whose output signals arerelatively free from errors and which is capable of prolonged use withminimal maintenance.

A still further object of the invention is to provide a keyboard encodercharacterized by simplicity of design and low-cost fabrication.

Briefly, switching apparatus embodying the invention includes a panelhaving opposed inner and outer surfaces. An elongated switchbar havingfirst and second ends longitudinally spaced apart and opposed top andbottom surfaces is disposed in an aperture through the panel anddepressable from the outer surface of the panel. The switch bar also hasan electrical element mounted adjacent its bottom surface thereof formovement with the switch as it is depressed. A first pair of first andsecond sensing elements and a second pair of third and fourth sensingelements are disposed inwardly from the bottom surface of the switchbar.Each sensing element in the first pair are closer to a first end of theswitchbar than are the sensing elements in the second pair. Each of thesensing 7 elements is electrically coupled with the electrical elementson the bottom surface of the switchbar and has a variable electricalcharacteristic selected from the two characteristics impedence andattenuation. The first and third sensing elements are connected togetherso as to combine their electrical characteristics and the second andfourth elements are connected together so as to combine their electricalcharacteristics. The sensing elements and the electrical elements are soarranged that the combined characteristics of the first and thirdelement change by substantially the same relative amount as the combinedcharacteristics of the second and fourth sensing elements when theswitchbar is depressed to change the position of the electrical elementsrelative to any one of the first pair of elements the second pair ofelements and both pair of elements. By positioning one pair of thesensing elements beneath one end of the elongated switchbar and theother pair of elements beneath the other end thereof, andinterconnecting the elements of the two pairs in the manner aforesaid,the change in impedance or attenuation characteristic, as the case maybe, is substantially the same when the bar is pushed down at only oneend as when it is pushed down so as to be parallel to the plane in whichthe sensing elements are disposed.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

BRIEF DESCRIPTION OF THE DRAWING In the accompanying drawings likereference characters denote like components, and:

FIG. 1 is a pictorial representation, partly broken away, of anelectronic display unit incorporating a keyboard encoder embodying theinvention;

FIG. 2 is a schematic representation of a keyboard encoder embodying theinvention and employing variable capacitors to sense actuation of thevarious keyboard buttons;

FIG. 3 is an exploded view of the keyboard of FIG. 1;

FIG. 4 is a fragmentary side elevation view, partly in section, of thekeyboard of FIGS. 1 and 3; and

FIGS. 5 and 6 show different constructions for a space button for akeyboard embodying the invention.

DESCRIPTION OF PREFERRED EMBODIMENT For a detailed description of theelongated switchbar apparatus embodying the present invention, referenceis made to the aforementioned U.S. Pat. No. 3,588,875, which patent isincorporated herein by reference. In particular, the elongated switchbarapparatus embodying the invention is shown in FIGS. 1 through 6 anddescribed in detail beginning at column 3 line 61 through column 6, line2 and beginning at column 10, line 69 through column 12, line 32.

I claim 1. Switching apparatus comprising in combination A. a panelhaving opposed inner and outer surfaces,

B. an elongated switch bar 1 having first and second ends longitudinallyspaced apart, and opposed top and bottom surfaces,

2. disposed in an aperture through said panel and depressible from theouter surface of said panel,

3. having an electrical element mounted adjacent said bottom surfacethereof for movement therewith,

C. means forming a first pair of first and second sensing elements and asecond pair of third and fourth sensing elements,

1. said sensing elements being disposed inwardly from said bottomsurface of said switch bar,

2. each sensing element in said first pair thereof being closer to saidfirst end of said switch bar than each sensing element in said secondpair thereof,

3. each sensing element being electrically coupled with said electricalelement and having a variable electrical characteristic selected fromthe two characteristics impedance and attenuation, the value of saidcharacteristic being determined by the position of said electricalelement relative to the sensing element,

4. said first and third sensing elements being connected together so asto combine their said electrical characteristics, and said second andfourth sensing elements being connected together so as to combine theirsaid electrical characteristics, and 5. said sensing elements and saidelectrical element being so arranged that the combined characteristicsof said first and third sensing elements change by substantially thesame relative amount as the combined characteristics of said second andfourth sensing elements when said switch bar is depressed to change theposition of said electrical element relative to any one of said firstpair of sensing elements, said second pair of sensing elements, and bothpairs of sensing elements. 2. Apparatus as defined in claim 1 in whichsaid sensing elements are disposed substantially co-planar with eachother and uniformly spaced from said panel.

3. Apparatus as defined in claim 1 in which A. each sensing elementcomprises an electrical conductor,

and

B. the conductors in each pair thereof are disposed side by side witheach other in the direction transverse to the longitudinal direction ofsaid switch bar and transverse to the direction in which said buttonmeans is depressible.

4. Apparatus as defined in claim 1 in which A. each sensing elementcomprises an electrical conductor,

B. the conductors in each pair thereof are disposed side by side witheach other in the direction in which said switch bar is elongated, and

C. said first and second conductors are successively ordered from saidfirst end of said switch bar the same as the successive order of saidthird and fourth conductors from said second end of said switch bar.

5. In an electronic keyboard encoder, the combination of A. a panelhaving opposed inner and outer surfaces,

B. an insulating board disposed inwardly from the said panel,

C. an elongated spacebar 1. having first and second ends spaced apartalong the direction in which said spacebar is elongated,

2. having a flat elongated bottom surface,

3. carrying a coupling element forming an electrically conductivesurface proximate to and substantially parallel to said bottom surface,

4. disposed in an aperture through said panel and depressible to movesaid coupling element toward said insulating board,

D. a first pair of first and second capacitor plates and a second pairof third and fourth capacitor plates,

1. said plates being on said insulating board and aligned opposite saidcoupling element,

2. said first pair of plates being closer to said first end of saidspacebar than said second pair of plates,

E. means connecting said first and third plates together,

F. means connecting said second and fourth plates together,

G. said plates being so spacially arranged that the sum of the spacingsbetween said coupling element and each of said first and third plateschanges by substantially the same relative amount as does the sum of thespacings between said coupling element and each of said second andfourth plates when said spacebar is depressed to change the spacingsbetween said coupling element and each pair of plates by the same amountas well as and by different amounts. 6. Electrical switching apparatuscomprising in combination A. a support,

ing on it which also acts on said coupling means, (2) said first andthird sensing elements bemg connected together so as to combine theirassociated transfer functions and said second and fourth sensingelements being connected together so as to combine their associatedtransfer functions,

(3) the position of said coupling means relative to said pairs ofsensing elements being different in said different depressed positions,and

(4) said sensing elements and said coupling means being so disposed thatthe combined transfer functions associated with said first and thirdsensing elements change movement substantially the same relative amountas the combined transfer functions associated with said second andfourth sensing elements when said switch bar is moved to any one of itsdepressed positions.

7. Electrical switching apparatus comprising A. a support, B. a switchbar elongated between first and second ends,

1. said switch bar having opposed inner and outer surfaces, and beingmounted for movement along a first direction parallel to the spacingbetween said inner and outer surfaces from a normal position to anactuated position,

C. first and second plunger elements spaced apart along said bar, eachplunger element 1. being movable along said first direction, and

2. being moved in said first direction by said button upon movement ofthe nearer end of said button toward said depressed position,

D. means forming first and second electrical sensors 1. each sensorbeing associated with one of said plunger elements, 2) each sensorcomprising a sensing element and an electrical element carried on saidassociated element, (3) each sensing element a being relatively fixedlymounted with said support and disposed adjacent said associatedplungerelement so that movement of the plunger element in said first directionmoves the electrical element thereon relative to the sensing element andchanges a field acting on the sensing element, and

(b) having an electrical transfer function the value of which isdetermined by said field acting on it,

4 said first and second sensing elements being connected together so asto combine their said transfer functions.

1. Switching apparatus comprising in combination A. a panel havingopposed inner and outer surfaces, B. an elongated switch bar 1 havingfirst and second ends longitudinally spaced apart, and opposed top andbottom surfaces,
 2. disposed in an aperture through said panel anddepressible from the outer surface of said panel,
 3. having anelectrical element mounted adjacent said bottom surface thereof formovement therewith, C. means forming a first pair of first and secondsensing elements and a second pair of third and fourth sensingelements,
 1. said sensing elements being disposed inwardly from saidbottom surface of said switch bar,
 2. each sensing element in said firstpair thereof being closer to said first end of said switch bar than eachsensing element in said second pair thereof,
 3. each sensing elementbeing electrically coupled with said electrical element and having avariable electrical characteristic selected from the two characteristicsimpedance and attenuation, the value of said characteristic beingdetermined by the position of said electrical element relative to thesensing element,
 4. said first and third sensing elements beingconnected together so as to combine their said electricalcharacteristics, and said second and fourth sensing elements beingconnected together so as to combine their said electricalcharacteristics, and
 5. said sensing elements and said electricalelement being so arranged that the combined characteristics of saidfirst and third sensing elements change by substantially the samerelative amount as the combined characteristics of said second andfourth sensing elements when said switch bar is depressed to change theposition of said electrical element relative to any one of said firstpair of sensing elements, said second pair of sensing elements, and bothpairs of sensing elements.
 2. disposed in an aperture through said paneland depressible from the outer surface of said panel,
 2. having a flatelongated bottom surface,
 2. said first pair of plates being closer tosaid first end of said spacebar than said second pair of plates, E.means connecting said first and third plates together, F. meansconnecting said second and fourth plates together, G. said plates beingso spacially arranged that the sum of the spacings between said couplingelement and each of said first and third plates changes by substantiallythe same relative amount as does the sum of the spacings between saidcoupling element and each of said second and fourth plates when saidspacebar is depressed to change the spacings between said couplingelement and each pair of plates by the same amount as well as and bydifferent amounts.
 2. being moved in said first direction by said buttonupon movement of the nearer end of said button toward said depressedposition, D. means forming first and second electrical sensors
 2. eachsensing element in said first pair thereof being closer to said firstend of said switch bar than each sensing element in said second pairthereof,
 2. Apparatus as defined in claim 1 in which said sensingelements are disposed substantially co-planar with each other anduniformly spaced from said panel.
 3. Apparatus as defined in claim 1 inwhich A. each sensing element comprises an electrical conductor, and B.the conductors in each pair thereof are disposed side by side with eachother in the direction transverse to the longitudinal direction of saidswitch bar and transverse to the direction in which said button means isdepressible.
 3. each sensing element being electrically coupled withsaid electrical element and having a variable electrical characteristicselected from the two characteristics impedance and attenuation, thevalue of said characteristic being determined by the position of saidelectrical element relative to the sensing element,
 3. carrying acoupling element forming an electrically conductive surface proximate toand substantially parallel to said bottom surface,
 3. having anelectrical element mounted adjacent said bottom surface thereof formovement therewith, C. means forming a first pair of first and secondsensing elements and a second pair of third and fourth sensing elements,4. disposed in an aperture through said panel and depressible to movesaid coupling element toward said insulating board, D. a first pair offirst and second capacitor plates and a second pair of third and fourthcapacitor plates,
 4. said first and third sensing elements beingconnected together so as to combine their said electricalcharacteristics, and said second and fourth sensing elements beingconnected together so as to combine their said electricalcharacteristics, and
 4. Apparatus as defined in claim 1 in which A. eachsensing element comprises an electrical conductor, B. the conductors ineach pair thereof are disposed side by side with each other in thedirection in which said switch bar is elongated, and C. said first andsecond conductors are successively ordered from said first end of saidswitch bar the same as the successive order of said third and fourthconductors from said second end of said switch bar.
 5. In an electronickeyboard encoder, the combination of A. a panel having opposed inner andouter surfaces, B. an insulating board disposed inwardly from the saidpanel, C. an elongated spacebar
 5. said sensing elements and saidelectrical element being so arranged that the combined characteristicsof said first and third sensing elements change by substantially thesame relative amount as the combined characteristics of said second andfourth sensing elements when said switch bar is depressed to change theposition of said electrical element relative to any one of said firstpair of sensing elements, said second pair of sensing elements, and bothpairs of sensing elements.
 6. Electrical switching apparatus comprisingin combination A. a support, B. an elongated switch bar mounted withsaid support for movement to different depressed positions, C.electrical coupling means mounted for movement with said switch bar, D.means forming a first pair of first and second electrical sensingelements and a second pair of third and fourth electrical sensingelements,
 7. Electrical switching apparatus comprising A. a support, B.a switch bar elongated between first and second ends,